I strongly suggest you stay on the stock firmware. Nowhere near as much refining & testing goes into updates compared to the original optimized package. When people update they are gambling the features they use/depend on (gps, wifi, BT, MMS - they can break with an update along with many other things) to gain trivial ones they won't. Never worth it.
The way lollipop handles sounds/notifications alone is a disaster and that's before any bugs lollipop may give you.